This invention relates to apparatus for transferring fluid from a fluid conveying line into a ship and, in particular, to apparatus including a transfer unit and positionable coupling element for effecting transfer of oil into a tanker.
The use of increasingly larger tankers makes it more and more difficult to bring these ships into a harbor for the purpose of loading oil since frequently the water is not deep enough and maneuverability is decreased. For that reason, oil transfer systems have been developed which are positioned either in the immediate vicinity of oil production platforms or off the coast of oil producing countries.
A typical oil transfer system, which is connected with the platform or with the oil storage tanks on land by means of an oil conveying line, includes a buoy which floats freely on the surface of the water. In order to load the tanker, the oil line in the oil transfer system is connected with the line belonging to the tanker by means of a coupling mechanism. However, wind and high seas may produce considerable relative movement between the buoy and the tanker and, under adverse weather conditions, it is often impossible to establish a coupling for transfer of the oil. It has been found that due to their dependence on weather, known off-shore oil transfer systems can be utilized, on the average, only 65% of the time.
In order to overcome this drawback, Japanese Pat. No. 42-24698/1967 discloses the off-shore anchoring of an oil transfer unit which is connected with an oil conveying line in such a manner that the oil transfer unit normally floats at the surface of the water. When a tanker is to be loaded or unloaded, the transfer unit is lowered by appropriate signals transmitted from the ship or a control center over electrical power cables to underwater winches disposed at the anchoring location so that the tanker can be positioned above the transfer unit. Once the correct position has been attained, the transfer unit is brought into contact with the bottom of the ship by paying out or retracting the anchoring cables.
By making accessible the space in the transfer unit where the connecting studs are disposed, these studs can be connected to the studs in the ship by means of hoses. However, with this system, automatic coupling is impossible and, when at the surface of the water, the transfer unit is exposed to all of the disturbances occurring there and is thus endangered. Further, existing requirements for placing such systems into operation are not met.
French Pat. No. 70.35460 discloses a system in which an anchor provided with pipe studs is placed at the bottom of the sea. An oil conveying line is connected to the anchor and a hose is coupled to the studs by means of a connecting head. A buoy is fastened to the connecting head by means of a chain, and the hose, connecting head and buoy are disposed at the bottom of the sea.
A tanker which is to be loaded or unloaded is positioned at a given location with respect to these components of the system and transmits signals to the buoy which cause a balloon to be inflated and a cover broken causing the balloon to rise to the surface. The balloon, and with it the connecting head, are taken aboard the tanker and the connections required for the oil transfer process are then made. After completion of the loading or unloading process, a new buoy is attached to the connecting head and lowered into the water where it sinks to the bottom.
A significant drawback of this system is that the retrieval of the balloon is extremely difficult, at least under poor weather conditions. Moreover, if the weather is bad, the hose will be subject to great stresses once the connecting head has been taken aboard.
It is therefore an object of the present invention to provide an oil transfer apparatus which permits coupling the oil line to the tanker and thus permits utilization of the system under adverse conditions.